git: unset conflictStyle

diff3 adds a lot of lines to do the conflict,
which can make it harder to understand in full sometimes.

especially when the lsp is just filling it with errors

defaults/git.nix

@@ -30,7 +30,6 @@ in
 
         push.autoSetupRemote = true;
 
-        merge.conflictStyle = "zdiff3"; # easiest to understand style
         commit.verbose = true; # show diffs in commit editor
       };
     };